The present invention relates to an apparatus for cleaving thin rods of glass or quartz (silica) having a diameter below 1 mm as well as a method for carrying out such a cleaving.
Although the invention is in general directed to cleaving such thin rods of glass or quartz for any subsequent use, the invention is particularly directed to cleaving such thin rods of quartz in the form of optical fibres. The invention and the problem to be solved thereby will therefor hereinafter by way of example be discussed for cleaving such optical fibres without limiting the scope of the invention.
Optical fibre ends are commonly prepared for a variety of purposes (jointing, characterization etc) by a process known as cleaving. In such a process, a blade prepared from a hard material, such a diamond, is brought into a lateral engagement with the fibre to be cleaved in such a manner as to initiate a fracture which subsequently propagates through the fibre cross-section until the fibre parts. The resulting cleaved fibre end surface should, as far as possible, be optically flat and perpendicular to the fibre longitudinal axis. Undue intrusion of the blade into the fibre during the cleaving process can damage the fibre so as to detract from the quality of the resulting end surfaces.
An apparatus is already known through U.S. Pat. No. 4,790,465. By using such a driving means for superimposing a relatively small-amplitude vibratory component of movement towards and away from the cleaving point to a relatively steady movement towards the cleaving point it has turned out that an anvil for supporting the optical fibre at the cleaving point is superfluous. This means that it will be easier to accurately monitor the cleaving process for improving the result thereof. However, it is emphasized that the present invention is not restricted to an apparatus having no such anvil, but also apparatuses with a supporting anvil are conceivable.
The apparatus according to said US-patent needs frequencies above 1 kHz for said vibratory component of movement, and in fact frequencies above 20 kHz are used there. Although the apparatus of U.S. Pat. No. 4,790,465 may be used for obtaining comparatively high quality cleaved fibre end surfaces there is of course always a desire to improve such an apparatus with respect to both the cleaving result and the construction and by that the costs for manufacture and operation thereof.